Late car dispatching from high call



5 Sheets-Sheet 1 l7 l7 1 m: g/s/a I E B. THURSTON LATE CAR DISPATCHING FROM HIGH CALL Filed Aug- 4. 1954 N .8 fiLm Mww m: R m N 0 4 6 E 1 U V 2 l a 2 H 411 i r "W J p a 2 x a l I. W mda p/ q. E M m I o o o F o o o o N J. o 0 o p o 0 0 0 m P o o o o o 3% w l o D o o o o o o o o o o o 0 Z M r o o o p o o o o J a a w b 4 2 l m 7 9 4 Dec. 3, 1963 Dec. 3, 1963 E. B. THURSTON 3,112,815

LATE CAR DISPATCHING' FROM HIGH CALL IN VEN TOR.

.-- E ER/VEST 5. THURSTUN Dec. 3, 1963 Filed Aug. 4. 1954 E. B. THURSTON LATE CAR DISPATCHING FROM HIGH CALL 5 Sheets-Sheet 4 Dbl-45,16: 2 1 1 L RELEASE IN V EN TOR.

United States Patent Ofiice 3,1 12,815 Patented Dec. 3, 1963 This invention rel-ates to elevator control circuits and in particular to circuits suitable for use in passenger operated elevator systems equipped with dispatching mechanism that may be conditioned according to expected passenger demand.

Passenger elevator installations have been equipped with dispatching mechanism that is arranged to dispatch the cars at such times as to render the best possible service according to the expected passenger traiiic demands. Thus during the morning when most of the passenger trafiic is from the lobby floor the elevator cars are dispatched regularly from the lobby floor and are reversed for return to that floor as they reach their highest call for service. At noon and in the late afternoon when the traific is predominantly toward the lobby floor the dispatching mechanism is arranged to dispatch the cars at uniform time intervals from the upper terminal and to return the cars to the upper terminal as soon as they are unloaded at the lower terminal. At other times during the normal business day the traffic is more or less evenly divided between up trafiic and down traffic. To satisfy this type of demand for service the elevators are dispatched from both terminals at more or less uniform intervals of time. It occasionally happens during the balanced trailic program that a car or cars may be delayed or be running behind schedule. In such cases time is lost by requiring the up traveling cars to go to the top floor and then backbefore answering down calls.

The principal object of this invention is to provide a control system for a bank of elevators that are operated without attendants arranged so that in the event that an elevator car is behind schedule in approaching the upper terminal fioor or is behind schedule in approaching the lower terminal the control is conditioned to reverse that or another up traveling car at its highest call.

Another object of the invention is to reverse up traveling oars at their highest calls whenever there are no cars available for dispatching at either of the terminal floors.

A still further object of the invention is to provide an elevator control system that reverses up traveling cars at their hig 165i calls only so long as there are no cars available for dispatching and in which normal terminal to terminal travel is re-estalblished upon the reversal of an up traveling car either at its highest call or the upper terminal.

Another object of the invention is to provide means for suppressing a dispatching signal at the upper terminal when a car is reversed prior to arrival at such terminal.

These and more specific objects and advantages are obtained from an elevator control system constructed according to the invention.

According to the invention an up traveling car is reversed at its highest call whenever there are no cars available for dispatching at either terminal floor at a time immediately prior to the transmission of a dispatch signal. The control is returned to normal terminal to terminal travel and regular dispatching from both terminals immediately upon the reversal of an up traveling car whethor it be at its highest call or at the upper terminal.

A preferred embodiment of the invention is illustrated in the accompanying drawings illustrating circuit-s employed in the improved control. e

in the drawings:

FlGURE I is a simplified schematic diagram illustrating a plurality of elevators to serve a plurality of floors.

. FEGURE H is a simplified schematic diagram of a floor selector machine for one of the elevators.

FIGURE Ill is a simplified schematic diagram of one. of the dispatching machines that is arranged to give dispatching signals to the elevators.

FIGURE IV is a schematic wiring diagram of the floor call registering equipment and the cooperating parts of an elevator control that serve to stop a car in response to hall calls.

lGURE V is a simplified schematic diagram of a circuit for locating the highest call that a particular elevator is to service.

FIGURE VI is a schematic wiring diagram of the power supply circuits for the dispatching machine motors. FIGURE Vii is a simplified schematic wiring diagram of the relay system for selecting the cars to be dispatched from the terminal floors and the relay system for each car readily applied to systems having any number of cars.

In the following description the control circuits are shown in connect-ion with a bank of elevators having four cars. The description does not differentiate between the cars in go oral and where such difieren-tiation is required in special cases the cars are individually numbered from ll through 4- and such designation is appended to the other reference characters.

Referring to FIGURE 1 a bank of elevators having car lltl are arranged to serve a plurality of floors each of which is equipped with hall buttons 11 operatively connected to the control mechanism that moves the cars it Each of the cars Jill are supported by a cable 12 trained over a drive pulley i and connected to a counterweight 14. The drive pulleys -13 are mounted on armature shafts :15 of elevator drive motors .16. The shafts 15 are also operatively connected either directly or through gearing tofioor selector machines 17. Preferably the driving connection from the motor armature shaft 15 to the floor selector machine 17 includes a slippable connection and control mechanism responsive to the position of the elevator car as it stops for each of the floors so as to continuously correct the floor selector machines 17 to agree with the actual position of the car.

The hall buttons 11 are arranged with a singlebutton at each of the terminal floors and a double button at each of the intermediate floors. The double buttons are arranged one for registering an up call and the other for registering a down call. These buttons are effective for stopping any of the cars and the calls are ordinarily answered by the first car to approach the floor while traveling in the direction indicated by the button.

FIGURE II shows one of the floor selector machines 17 in greater detail. As shown the floor selector machine includes a panel board which may be a series of horizontal strips carrying a plurality of contacts 18. The contacts 18 are arranged in horizontal rows according to the floors served by the elevator and are arranged in vertical rows or lanes according to the functions controlled by the respective contacts. Thus there is a verti- 35 cal row or lane of contacts to control the position indicating lights of the car, another lane to control the stopping circuits in response to floor calls, another lane of contacts serves to stop the car in response to car calls, another lane to reset the hall call controls, as well as other lanes to control switching functions that must be operated as the car travels up and down the elevator hatchway. Of particular interest in connection with the dispatching control circuits according to the invention are contacts 20 and 2;]; of each of the floor selector machines that cooperate with brush 2.2 of a traveling carriage 2 3 that is moved up and down across the face of the contacts 18 as the elevator moves up and down the hatchway. The carriage -3 is driven from the armature shaft of the elevator drive motor through a gear reduction and correction device '24 and lower drive shaft 255 carrying sprockets 2.6 that engage chains 2'7 carrying the carriage 23:. The chains 27 are guided over upper sprockets 28 and may support a counterweight on the rear side of the floor Selector machine to balance the weight of the carriage 23. Electrical connections to the brushes of the carriage 2.3 are made through a flexible cable 2% attached to a rigid support point 353 and to the carriage 23.

Another set of contacts 3d and 32 of the floor selector machine that cooperate with a brush 35 are also of interest in regard to dispatching since these contacts, which are arranged to be contacted by the brush 33 as the elevator departs from the terminal floors, are arranged to reset the dispatch signal control mechanism. Contacts 2% or 21 of each of the floor selector machines are contacted by the brush 22 when the elevator is standing at the corresponding terminal fioor. These contacts, as will be described later, are included in the dispatching selector cir cuits and in combination with such circuits indicate the presence or absence of ele'vator cars at the terminal floors available for dispatching.

FIGURE III illustrates, in simplified form, a dispatching machinejfor generating dispatching signals at substantially equal intervals of time. This machine includes a direct current drive motor 35 which is connected through a gear reduction box 36 to drive a cam disk 37. The cam disk 37 has a projection 33 which as it moves or rotates clockwise first closes a set of contacts B and then a short time later closes a set of contacts A, contacts A are shown closed in the diagram. The drive motor 35 is preferably a direct current motor which is energized by variable voltage direct current according to a circuit shown in FIGURE VI to provide variations in timing intervals.

The remaining figures of the drawings illustrate in schematic form some of the circuits used in the control of the elevator according to the invention.

In order to simplify the showing of these circuits the relay operating coils and contacts are given similar reference characters. The number of contacts and their 10- cations operated by each coil is found by reference to a code running along the right side of each of the figures. This code opposite each operating coil lists the line numbers in which the contacts operated by each coil are located. An underscored line number indicates that the corresponding contact is closed when the coil is de-energized. Since only a small portion of the total number of relays and contacts employed in an elevator system are shown a number of the contacts have no operating coils shown.

FIGURE IV of the accompanying drawings illustrates the floor call circuits and the stopping relay arrangement for stopping the cars in answer to registered floor calls. Since the circuits are similar, only the circuits for the first, fifth, tenth, fifteenth and twentieth floors are shown. As shown in this diagram floor calls are registered by means of the hall buttons 11 one for each direction of travel for each of the intermediate floors. Pressing a floor button for example the floor button 11 shown near the left end of line 18 allows current to flow from the line L1 through trip coil of the tenth floor latch relay MU and then through the now closed push button 11 to a lead it connected to the return line L2. The current flow through the trip coil trips the relay so that it thereupon closes its contacts ltlU in line 6. Thus an up call is registered from the tenth floor and such call remains registered until the latch relay for the tenth floor up calls is reset. Closure of the contacts illU in line 6 energizes the corresponding selector machine contact 41 of each of the selector machines. (These contacts are connected in parallel as indicated by the arrow tipped branch lead.) When the next up traveling car approaches the tenth floor its selector brush 42 upon contacting the now energized contact 41 allows current to flow through a lead &3, up direction contacts UF in line 3, then through the rheostat contacts RLS and bypass relay contacts BP in line 2, then through a stopping relay operating coil S and brake contacts K of line 2. The bypass contacts B? are arranged to be closed as long as the car is in conditionto answer all calls. These contacts are open as soon as the conventional bypass switch in the car is operated, The contacts RL3 of the rheostat are part of the control mechanism to prevent the stopping relay from operating as a car is leaving a floor in the event that a second call is registered for the floor before the car is ready to leave. Energization of the stopping relay S completes a circuit from the lead Ll through a lead 4-4, contacts VRl, and stopping relay contacts S in line l to establish a holding circuit for the stopping relay S and thus allow the iloor relay iliU to be immediately reset.

It is desirable to reset the floor relays as soon as possible after a signal is picked up by one of the elevator cars in response to a hall call. This is to prevent other cars which may be following closely upon the car answering the call from stopping in response to that hall call. in the circuit shown, operation of the S relay in line 2 starts a series of operations through relays including a motor stopping relay VRZ having contacts in line 13.

Closure of the contacts VR2 in line 13 allows current to flow from the lead Lll through reset coils MU of the tenth floor relay in line 12, thence through its selector machine contact 45 and brush 4-6 to a lead 417, thence through up directional relay contacts UF in line 14 and through bypass relay contacts BP and the now closed VRZ contacts in line 13. This circuit, which is completed as soon as the call is registered in the stopping circuit of the elevator, resets the tenth fioorhall call relay so as to cancel the signal on the selector machine contact 41 so that other cars will not stop in response to the previously registered call.

Calls for service in the down direction are similarly registered by tripping the coils of the down latch relays by current flow from the lead Ll through a lead 5t; and through the trip coil of the corresponding latch relay as connected by its push buttons llll shown'near the center of FIGURE IV in lines 116, 19 inclusive. Upon tripping one of the down call relays it closes its corresponding contacts in lines t, 5, 6 or '7 so as to prepare circuits to be completed through a brush 5d of the selector machine and leads 52, contacts DF in line 3 and then through the stopping relay S. Likewise as soon as a car proceeding in the down direction answers the call by having its stopping relay S energized it resets the tripped relay by current flow from the lead 5t} through the corresponding reset coil in lines lid to 13 inclusive and a brush 5'3 and a circuit including the down directional contacts DP shown in line 13, the bypass relay' contacts BP and the VRL; relay contacts. It should be noted that the stopping relay S is dc-energized as soon as the brake relay BK releases as the car stops in answer to the call.

Referring now to FIGURE V each of the floor call latch relays such as the relays 1U, 5U, 51), NH, ND etc. of FIGURE IV has normally closed contacts, i.e., contacts that are closed as long as no call is registered, and these contacts are arranged in a series circuit as shown in FIGURE V and connected from the first line Ll through a lead 6d, down contacts 20D of down floor relay 29]), up and down contacts of the floor relays and finally to a lead 61 that is connected through a floor call service relay operating coil SS in line 30 and then to the return lead L2. This circuit is complete to en ergize the SS relay coil as long as there are no hall calls registered.

The common connection between the up relay contacts and the down relay contacts for each floor are connected to floor selector machine contacts 62 for each of the elevators. These contacts d2, there being one for each floor on each floor selector machine, cooperate with brushes 63 that are connected through a circuit including, in series, program switch contacts H2 line 25, express-local relay contacts EL, car button switch relay contacts CBS, up direction contacts UF, rheostat con tacts EH3, and a high call timing relay coil I-ICT. The program selector contacts H2 are in parallel with late car reversal relay contacts LCR. The program contacts H2 in line 25 are closed on all except the balanced up and down traffic program. The express-local relay contacts EL are closed as long as the car is conditioned for local traffic. If that car is selected for express trafiic, that is, operation between the upper floors and the lower terminal without stopping at lower floors these contacts are open. Car button switch contacts CBS in line 25 are closed as long as there are no registered calls from the call buttons for floors above the car. This circuit is completed to energize the l-ICT relay whenever an up traveling car, on local service and on any program other than balanced up and down trafiic, reaches a position at which there are no further hall calls or car calls for floors above it. The circuit is energized by way of current flow from the lead Ll through the lead 61} and the normally. closed contacts energizes all the contacts in corresponding to the floors above a hall call. The circuit to the high call timer relay IICT is completed when the brush 63 reaches one of the energized contacts. The high call timer relay I-ICT, as soon as it is energized, closes another relay coil I-lC (that is not shown in the drawings) and this relay in turn operates its contacts I-IC appearing in lines 2 and 9 of FIGURE IV as Well as contacts appearing in line 66 of FIGURE VII.

If the elevator system is operating on high call reverse, the condition for high or heavy up traffic as occurs in the morning hours when tenants of a building are coming to work or is operating on heavy down traffic when the cars are to be reversed or started downward as soon as they have reached their highest call, contacts H1 or H3 in lines 9 and ill of FIGURE IV are closed. Under this condition when an up traveling car reaches its highest call (so that the circuit shown in FIGURE V is completed to energize the high call relay and close contacts HQ in line 9) current flows from the lead 5%, FIGURE IV, through the down fioor call selector machine con tacts 65 of the highest down call to energize the brush 51. Since the elevator is traveling up at this time the contacts DF in line 3 are open. However, current can now flow from the brush 51 through the high call relay contacts HQ in line i and thence through down stop relay operatingcoil SD in line 9, and the now closed con-' tacts H1 or H3 to the return lead L2. Energizing the down stop relay SD causes it to close its contacts SD in line 66 of FIGURE VII. to effect an immediate reversal of the directional latching relay RL. The directional latching relay RL thereupon conditions itself for down travel of the elevator car and in so doing closes its contacts RI. in line 2, FIGURE IV, so as to complete a circuit from lead L1 through lead 44- in line I, thence through the hi h call relay contacts HQ in line 2, now closed directional latch relay RL contacts, the rheostat contacts RL3 and bypass contacts 8? to the stopping relay coil S in line 2. The up traveling elevator car is thereupon shown in FIGURES VII and VIII.

brought to a stop at that floor with the indicating lights and the control circuits conditioned for down travel.

FIGURE VI shows in simplified form the circuit for energizing the motors that drive the timing mechanism connected with the dispatching equipment. In order to maintain the greatest possible etfic-iency in dispatching the elevator cars and in order to keep the cars balancedbetween up and down travel insofar as is possible two dispatching machines are employed, one for the top terminal and the other for the bot-tom terminal. The machines are ordinarily adjusted to run at the same speed and to provide dispatching signals at generally equal intervals of time. Additional control circuits are provided so that in the event two or more cars stop simultaneously at one of the terminals that particular dispatching machine is speeded up and the machine at the other terminal is slowed down unless there are two or more cars also awaiting dispatching at that terminal. Each of the dispatching machines is detented or stopped whenever its dispatching time interval elapses or is about to elapse Without a car being at the terminal in condition to respond to a dispatching signal. FIGURE VI shows the circuits for providing this control except for the means for speeding up one of the dispatchers and slowing down the other. In the circuit as shown alternating current power from leads LI and L2 is applied to an autotransformer '76 having a plurality of taps 71, 72 73, '74 and '75. An armature circuit for the top dispatching machine motor 76 is taken from the lead LI through rectifiers 77, 73, '79 and S0 and then through contacts DFD of a top terminal relay DFD and thence through a lead 81 to a selector switch arm 82 of a speed selector switch for selecting the speed of operation of the dispatching machines. A dispatching machine motor 83 for the bottom dispatching machine is also energized from the lead L1 through a circuit including rectifiers 8d, 85, 86 and 37 and bottom terminal dispatching relay contacts DU-D connected to the selector switch arm $2 of the autotransformer selector switch. Fields S3 and 39 of the motors '76 and 83 respectively are energized from a full wave rectifier 96) that is connected between the leads L1 and L2 and adapted to supply direct current to the fields as well as to leads L3 and L4 which supply direct current power to the circuits Contacts DFD, line 34, and DUD of line 38 remain closed at all times except when there are no cars available for dispatching at the respective floors. If no car is available near the end of dispatching time interval then the dispatching motor forthat terminal is stopped until a car arrives at the floor and is ready for dispatching.

Referring now to FIGURE VII the sequence in which cars are dispatched from the upper terminal is determined by the circuits shown in lines 4-5 to 52 inclusive while the circuits that select the cars at the lower terminal are shown in lines 56 to 63 inclusive. In these circuits selector machine brushes lltil for the first elevator, M2 for a second elevator, MP3 for a third elevator and 194 for a fourth elevator are connected to the positive direct current lead L3 through in service relay con-tacts 18(1), 18(2), 13(3) and 18(4). When the first elevator is at the unper terminal its brush 101 contacts a selector machine contact ze-r that is connected through an operating coil of a down loading relay DL]; and thence through DLll contacts in line 46 to a lead res that is connected through a series of normally closed contacts DLI, DLZ, DL3 and BIA of the down loading relays ot each of the elevators and then through an inductance coil lid? connected to the return lead L4. If there were no other cars at the upper terminal at the moment when the number 1 car arrived, none of the down loading relays would have been energized and therefore the circuit from lead 1% through the DL contacts in line 52 would be complete so that the first down loading relay DLI would be energized. As it is energized and closes its contacts DLI, line 45, it seals itself in and at the same time opens its contacts DLI,

7 line 46, to break the circuit to the lead 18-6 and its contacts DLll, line 52, between the lead 1% and the inductance coil 107. Should. another car arrive at the upper terminal before the first one left, and its brush 1'32, res, or 1134 contact the corresponding contacts lit-2, etc., of the selector machines, no current flows because the circuit through the series of DL contacts in line 52and inductance coil 107 is open by operation of the first down loading relay DLl. As soon as the first elevator leaves on its down trip and breaks the connection between its brush 191 and its contact 204, relay DLl releases and the series circuit is again completed so that the down loading relay for the next elevator may be energized. Should two or more cars be waiting as the first car left, one of the waiting cars is selected for dispatching. The selection is made according to the pull-in-current of the down loading relays DLl, DLZ, DL3 and Diedso that they pull at different amounts of current. Since the circuits are conditioned or closed except for one set of contacts in the series circuit that close when the first car leaves, the closure of these con-tacts allows current to build up in the several relay coils corresponding to the cars remaining at the terminal at a rate determined by the inductance coil 167 and that one which pulls in on the lesser current or least current will be the first one to operate. As it operates it opens the series circuit in line 52 and thereby prevents any of the other download relays from operating.

A similar arrangement is employed for the lower terminal having up loading relays ULl in line 56, ULZ in line 58, UL3 in line 6d and UIA in line 62. These relays are also energized one at a time according to the elevators present at the terminal floor and available for dispatching. If an elevator is standing at one of the terminal floors and is not available for dispatching, i.e., it is out of service for some reason, its in-service relay IS would be de-energizcd so as to de-energize its brush 101, M2, 103 or 164. Therefore the corresponding loading relay UL or DL would not be energized and therefore would not interfere with the selection for dispatching of the other cars that are still in service.

The directional control circuit for each car, which includes a latch relay RL for setting up the direction of travel for the elevator, is illustrated in the bottom portion of FIGURE VII. This latch relay RL has a trip coil RLT that is energized when the elevator reaches the bottom terminal and a reset coil RLR that is energized when the elevator reaches the top terminal or is to be reversed at some intermediate point without traveling to the top terminal. As shown in the diagram, the trip coil RLT shown in line 65 is energized from lead L3 by way of the operating coil of a car button reset relay RB, then lead 11%, trip coil RLT of the directional latch relay, then selector machine contact 111, brush 112 that engages the contact 111 when the elevator is at the bottom terminal and thence through lead 113 and norm-ally open contacts of the door opening relay OP and then through lead 114 to the return lead L4. The directional relay RL is reset at the upper terminal by current flow from the lead L3 through the car button reset relay RB thence through the reset coil RLR in line 66, lead 115 to the contact no corresponding to the top terminal which is contacted by the brush lllZ when the elevator reaches the top terminal. The directional relay RL may also be reset at intermediate fioors in the event the high call relay HC is operated so as to close its contacts HC in line 66 and the high call stop relay SD is operated so as to close its. contacts in line 66. One additional set of contacts from the down relay controls D are also included so as break this circuit through the reset coil RLR immediately after the relay is reset and the other control relays are energized accordingly. The SD contacts in line as are bypassed by a series arrangement of program contacts. H1 and stopping relay control contacts V R1 in line 63. The program contacts Hl are closed during up peak traffic conditions and the V111 contacts are closed momentarily as the elevator is slowing for a stop. The latch relay RL through its contacts in lines 68 and 69 controls up and down relays U and D which are in the nature of master relays to set up all of the circuits in the control system required to cause the elevator to operate in the proper direction.

During average trafi'ic conditions on an ordinary business day the elevator system is conditioned to give prompt service in either direction of travel. In this program the cars are dispatched at regular intervals from each of the terminal floors. The cars are dispatched substantially in order of arrival unless there are two or more cars remaining at a terminal floor when a car is dispatched from that floor. In that event selection of the remaining cars is made by the circuits in lines 52 or as according to the numerical order of the cars in the bank and is usually selected in one order in one terminal and the opposite order at the other terminal so as to equalize the use of the elevators insofar as possible.

It occasionally happens during sudden increases in traffic that an elevator car may not be available for dis patching at a terminal floor when the dispatching time interval, as measured from the departure of the last previous car, has expired or is about to expire. Under this condition it is necessary for best service to accelerate the dispatching of the cars as much as possible so as to get the cars in motion rather than holding them at the terminal floors. The situation that often occurs if there is a sudden increase in the number of stops to be made or one or more elevators is temporarily removed from service is that there is no car at one of the terminal floors and one or more are at the opposite terminal awaiting dispatch. In this situation better service may be afforded the intending passengers if the up traveling cars are reversed at their highest call and started down again thereby saving the time required for the cars to travel the extra distance. This reversal of up traveling cars is of advantage regardless of whether the lack of cars occurs at the upper or the lower terminal.

FIGURE VIII illustrates schematically circuits that are employed to provide reversal or high call operation of up traveling cars during such times as there are no cars available at one or the other of the dispatching floors and the dispatching time interval for that floor is about to expire or has expired. In the diagram shown in FIG- URE VIII down dispatching signals are given to cars at the upper terminal whenever contacts AT shown in line of the dispatching machine are closed by operation of the cam 37. These dispatching signals are given by re setting the down dispatch latch relay KD by current flowing from the lead L3 through the momentarily closed contacts AT, through the lower or resetting coil KB or" the dispatching relay, and then through normally closed contacts LCTA of a latecar auxiliary relay LCTA line 75'. The dispatching relay is tripped by circuits not shown that are completed upon the departure of any car from the upper terminal floor.

Whether or not-the dispatching signal is given depends upon whether or not the dispatching machine is allowed to run continuously. Once each revolution of the cam 37 contacts BT, shown in line 7'7, are closedshortly' before the expiration of the dispatching time interval. Closure of the contacts BT completes a circuit from the lead L3 to another lead 12%} and thence by Way of normally closed contacts D'L(l), DL(2), DL(3) and DL(4) (of down load relays DL) shown in line 76 to the operating coil of a down detenting delay relay DFDA in line 76. Current may also flow in line 77 by way of another series of down loading relay contacts DL(l), DL(2), DL(3) and DL(4) and normally closed contacts BD of a relay arranged to limit the number of cars that may remain at the upper terminal in the event that there are no calls for service from the first floor or the lower terminal. The contacts B1) are open whenever two or more cars are standing at the upper terminal. From the series circuit of the normally closed down loading relay contacts DL and the BD contacts the. circuit continues through normally open SS contacts of a hall call relay (FIGURE V) that is energized when there are no floor calls. From the hall call relay contacts SS current may flow through an operating coil of a down detent relay DFD in line 77 and then through normally closed contacts LCT A of the late car auxiliary LCTA. Each of the down loading relay contacts in this circuit is bypassed by normally closed contacts of a car call below relay CB-D, one for each car. In this circuit the down detent relay DFD,'line 77, is energized as long as there are no cars available for dispatching at the upper terminal, that is, if all of the down loading relays are de-energized so that the circuit is completed through line'77, and assuming that contacts BD are closed and there are no calls for service so that the contacts 88 are closed. The detent relay DPD may be energized even though a car is standing at the upper terminal if there are no car button calls registered in that car for lower floors. In this situation the car button relay CBD of the car that is standing at the terminal is de-energized so as to close its contacts in parallel with the now open down loading contacts DL of line 77.

The detent relay DFD in line 77, when energized, opens its contacts in line 34 of FIGURE VI so as to stop the top floor or top terminal dispatching machine and hold it stopped until there is a call for service. The detenting relay BBB is also energized in the event that (a) the elevator system is conditioned for heavy up trafiic such that the contacts H1 in line 80 are closed, (b) there is no car at the upper terminal available for dispatching such that the auxiliary detenting' relay DFDA, line 76, is energized to close its contacts in line 81 or (0) there are an unusual number of car calls being registered so as to close contacts CPA in line 79. In these cases the cars are immediately dispatched by means other than the dispatcher and the dispatchers are held inactive.

A similar arrangement is used for the bottom terminal in which case the dispatching signals are given by resetting a dispatching latch relay KU in line 82 by current flowing from lead L3 through the contacts AB in line 82. Likewise the bottom terminal dis-patching machine may be stopped by energizing an up detent relay DUD in line 84. This relay may be energized by way of contacts HPA in line 86 which are closed when there are more than a certain number of hall calls remaining to be answered or in the event the system is conditioned for down peak traiiic when the contacts H3 in line 87 are closed. The relay may also be energized by closing contacts of the up detenting auxiliary relay DFUA in line 88. 'Furthermore the relay may be energized in the event there is no car available at the bottom terminal for dispatching in which case the up loading relays UL of all of the cars are tie-energized. If this happens with a hall call registered so that contacts SS are closed the up dispatching machine for the bottom terminal is detented or stopped just prior to giving a dispatching signal. Thus, if the system is operating on down peak program, has an unusually large number of unanswered down calls which require down peak operation, or there are no cars at the bottom terminal available for dispatching the dispatching machine is stopped. I

To expedite service if there are no cars at the upper terminal available for dispatching when the contacts ET in line 77 close the down detent auxiliary relay DFDA in line 76 is energized to close its contacts in line 90*. If the system is operating on balanced trafiic program, that is, generally equal up and down trafiic so that contacts H2 in line 90 are closed, current may flow from the supply lead L3 through the now closed'contacts H2 in line 90 then through the down detent auxiliary relay contacts DFDA, to a late car reversal relay operating coil LCR, line 89, and then through normally closed contacts LCTA of a late car auxiliary relay LCTA and then to the re- 10 turn lead L4. Energization of the late car reversal relay LCR in line -89 closes its contacts in lines 8 and 24. C10- sure of the contacts LCR in line 8 prepares a circuit for the energization of the down car reverse relay SD in line 9 and closure of contacts LCR in line 24 to bypass the H2 contacts in line 25 sets up the regular high call reverse circuits. The up traveling car thereupon reverses as soon as it reaches its highest call.

Normal top terminal dispatching is maintained by contacts LCTA in line 75 as long as there are cars available at the top terminal. To restart the top dispatcher without giving a dispatch signal when a late car reverses with no car available at the top terminal a late car timing relay LCT in line 91 is arranged to be energized by the high call reverse relay SD in line 9. Since the high call reverse relay SD is only closed or energized momentarily a late car timing auxiliary relay LCTA in line 92 is arranged to be energized in parallel with the timing relay LCT and it has contacts LCTA in line 92 ar ranged in parallel with the contacts of the high call reversing relay SD so as to hold these relays LCT and LCTA energized after the high call reversing relay SD has operated. This relay LCTA which operates immediately upon reversal of a car opens its contacts LCTA in line 89 to tie-energize the late car reverse relay LCR and thus return the system to normal operation. The late car timing auxiliary relay LCTA also opens its contacts in line '77 so as to de-energize the down dispatching detent relay DFD in line 77 to permit the dispatching machine to run and also to break the circuit to the reset or lower coil of the down dispatching relay KD in line 75 so that this relay will not be reset to set up a down dispatch signal when the contacts AT close shortly after the dispatching machine again starts to run. This is necessary since the reversing car cannot cancel the signal. A short time later the late car timing relay in line 91 times out and opens its contacts in line $22 so as to de-energize the late car timing auxiliary relay LCTA and thus de-energize or open the circuit in line 92 thereby restoring the system to normal conditions for balanced up and down traffic. Should conditions still require high call reverse operation the circuits are again set up upon the next closure of contacts RT or BB of the machines.

It should be noted that in this arrangement the first car to reverse in its upward travel at an intermediate floor restarts the dispatching machine for the next dispatching signal.

This system therefore makes it possible in the event that there are no cars at either terminal floor for an up traveling car to be reversed and started down when it reaches its highest call. When it reaches its highest call and reverses it re-establishes normal operation of the dispatching machines leaving that one at the'upper terminal in condition to time a regular dispatching time interval before it again gives a down dispatching signal. Should the system have been thrown onto high car reversal by the absence of cars at the lower terminal the operation is similar in that the first up traveling car to reach its highest call reverses and starts back and such reversal re-establishes normal conditions. However, in this case there may have been another carat the upper terminal awaiting dispatch. This car at the uppe terminal in this situation is dispatched in its normal. order or normal time without taking any account of the reversal of the up traveling car. Since the circuit was thrown into high call reverse because of the absence of cars at the lower terminal this has the effect of advancing the dispatching at the upper terminal by one full step, in other words getting another car into the down cycle without waiting for the normal operation of the top terminal dispatching machine. Since the bottom terminal dispatching machine is detented by the absence of cars available for dispatching and since all cars are brought to the terminal it is unnecessary to interrupt the transmission of a dispatclfing signal to the up dispatch relay KU. Regular dispatching is maintained according to the demands.

Various modifications of the circuits may be made without losing the advantageous and simplicity of circuit structure for reversing late cars at their highest call and thereby offering more prompt service during temporary periods of heavy trailic demands.

Having described the invention, I claim:

1. in a control system for a bank of elevators, in combination, a timer having a first and a second set of contacts that are sequentially operated, elevator dispatchingmechanism controlled by the first set of contacts, a circuit including a series of contacts one for each elevator that is complete when no elevator car is at the terminal available for dispatching connected in series with said second set of contacts, a relay controlled by said series of contacts arranged to cause an up traveling car to reverse at its highest call, and means responsive upon reversal of an elevator for tie-energizing the relay. 7

2. In a control system for a haul; of elevators, in combination, timing means for producing dispatching signals, a series of relays each operable by the presence of a respective elevator car at a terminal floor, second means operating a timed interval in advance of the operation of said timing means, third means operative in response to the coincidence of operation of said second means While said relays indicate all effective cars are absent from said terminal floor, means controlled by the third means for causing an up traveling car to stop and reverse at the highest call for service, and means for releasing'the third means to an unoperated state upon reversal of a car.

3. In a control system for a bank of elevators, in combination, timing means, for producing regularly timed dispatching signals, a series of relays energized by presence of respective cars at a dispatching floor, a contact on each relay that is opened when the respective car is at the floor, a first control means, a contact on the timing means that is momentarily closed prior to the regular dispatching signal, a circuit including said timing means contact and the contacts of the series of relays for energizing the first control means, means controlled by the first control means for interrupting the timing means, a second control means that is energized by the first control means, means controlled by the second control means for stopping and reversing an uptraveling car at its highest call, and means responsive upon "the reversal of a car for restarting the timing means and tie-energizing the second control means.

4. In a control system for a bank of elevators, in combination, means for detecting the absence of cars available for dispatching at a dispatching floor, a dispatching machine for producing dispatching signals at generally regular intervals of time, a pair of contacts operated by the dispatching machine prior to production of a dispatch signal, a control means that is energized 'by operation of :said contacts and said detecting means when no car is :available for dispatch,imeans controlled by said control means for causing an up traveling car to reverse at its h ghest call, said control means also serving to stop said d spatching machine, a second control means that is eneriglzcd when an up traveling car reverses at its highest call, and means controlled by the second control means for restarting the dispatching machine and tie-energizing the high call reversing means controlled by the first control means.

5. In an elevator control system, means for reducing the travel of elevator cars when behind schedule and no calls are registered requiring full travel comprising, in combination, means for detecting the absence of cars available for dispatching at a dispatching terminal, a dispatching achine which enables a circuit a timed interval In advance of the generation of a dispatching sign '12 means actuated by the enabling of said circuit during absence of cars at the dispatching terminal for causing an up traveling car to reverse at its highest call, and means responsive upon the reversal of an up traveling car for releasing the high call reverse 1 1621118.

6. In an elevator dispatching control system, means for reducing elevator car travel to maintain a dispatching schedule comprising, in combination, a dispatching machine for generating dispatch signals at generally equal intervals of time, a pair of contacts that are closed for a short time prior to the generation of a dispatch signal, a series circuit of relay contacts that is opened by the presence of an elevator car at a terminal available for dispatching, an inactive high call reverse circuit for each elevator, means actuated by the simultaneous closure of said dispatcher contacts and relay contacts for stopping the dispatch machine and activating the high call reverse of each elevator car, and means responsive upon the reversal of an up traveling car for restarting the dispatching machine and de-activating the high call reverse circuits.

7. In an elevator dispatching control system, means for reducing elevator car travel to maintain a dispatching schedule comprising, in combination, a motor driven dispatching machine, a set of contacts on the machine that are momentarily closed a short time before the generation of a dispatching signal, a relay for each elevator, said relay being operated when the elevator car is at a terminal available for dispatching, said relays having contacts connected to complete a series circuit when the relays are de-energized, a control means that is energized through the dispatching machine contacts and the series circuit, an inactive high cell reverse circuit for each elevator, means actuated by said control means when energized to stop the dispatching machine, other means actuated by said first control means for activating the high call reverse circuits, a control relay that is energized upon the reversal of an up traveling car, means for holding the control relay energized for a predetermined time interval, and means on the control relay for restarting the dispatching machine and de-activating the high call reverse circuits.

8. In an elevator dispatching control system, means for reducing travel of empty cars that are late in following a predetermined dispatching schedule comprising, in combination, a dispatching machine for each terminal, contacts on each machine that are closed a timed interval in advance of a dispatching signal, a series of relays for each terminal, each series having a relay for each elevator that is operated when the elevator is at the terminal and available for dispatching, a control means for each terminal that is energized through the contacts of the corresponding dispatcher and series of relays, means operated by each said control means for stopping the corresponding dispatch machine, a high call reverse circuit for each elevator, means operated by said control means for engaging the high call reverse circuits, and means responsive upon the reversal of an up traveling car for de-energizing the control means.

9. In an elevator dispatching control system, in combination, a dispatching machine for each terminal for issuing dispatch signals, means for each machine for issuing a detent signal a timed interval in advance of each dispatch signal, a control means for each terminal, an energizing circuit for each control means that is actuated by the issuance of a detent signal by the dispatching machine when no car is at the terminal available for dispatching, means controlled by the control means for detenting the dispatching machine, a second control means that is energized by either of said control means, a high call reverse circuit for each elevator that is energized by the second control means, and means responsive upon the reversal of an up traveling car for d e-energizing the second control means and restarting the detent dispatching machine.

10. In an elevator system comprising a plurality of elevator cars serving a plurality of floors, means for causing said cars to stop at floors for which a demand for service has been made, timing means operable to provide signals for dispatching cars from a terminal floor at timed intervals and means for suspending operation of said timing means in advance of the issuance by said timing means of a signal for dispatching cars 'when no demand for service exists. V

11. In an elevator system comprising a plurality of elevator cars serving a bottom terminal floor and a plurality of upper floors, means for'c-ausing cars to stop at floors for which demands for service have'been made, timing means operable to provide signals for dispatching cars from said bottom terminal floor at timed intervals and means for suspending movement of said ears and operation of said timing means in advance of the issuance by said timing means of a sign-a1 for dispatching cars when no demand for service exists and when a car is at said bottom terminal.

12. In an elevator system wherein a plurality of eleva r tor cars serve a terminal floor and a plurality of other floors, means for registering demands for service, selecting means for choosing from among cars available for dispatching from said terminal door that car 'which first arrived at said terminal floor, as the next to leave said terminal floor, timing means for giving-dispatching signals and means, operable when no demand for service has been registered, for suspending operation of said timing means in advance of the issuance by said timing means of a signal for dispatching cars.

References Cited in the file of this patent UNITED STATES PATENTS 2,688,383 Eames Sept. 7, 1954 

3. IN A CONTROL SYSTEM FOR A BANK OF ELEVATORS, IN COMBINATION, TIMING MEANS FOR PRODUCING REGULARLY TIMED DISPATCHING SIGNALS, A SERIES OF RELAYS ENERGIZED BY PRESENCE OF RESPECTIVE CARS AT A DISPATCHING FLOOR, A CONTACT ON EACH RELAY THAT IS OPENED WHEN THE RESPECTIVE CAR IS AT THE FLOOR, A FIRST CONTROL MEANS, A CONTACT ON THE TIMING MEANS THAT IS MOMENTARILY CLOSED PRIOR TO THE REGULAR DISPATCHING SIGNAL, A CIRCUIT INCLUDING SAID TIMING MEANS CONTACT AND THE CONTACTS OF THE SERIES OF RELAYS FOR ENERGIZING THE FIRST CONTROL MEANS, MEANS CONTROLLED BY THE FIRST CONTROL MEANS FOR INTERRUPTING THE TIMING MEANS, A SECOND CONTROL MEANS THAT IS ENERGIZED BY THE FIRST CONTROL MEANS, MEANS CONTROLLED BY THE SECOND CONTROL MEANS FOR STOPPING AND REVERSING AN UPTRAVELING CAR AT ITS HIGHEST CALL, AND MEANS RESPONSIVE UPON THE REVERSAL OF A CAR FOR RESTARTING THE TIMING MEANS AND DE-ENERGIZING THE SECOND CONTROL MEANS. 